<%--
  Created by IntelliJ IDEA.
  User: WuLiangHang
  Date: 2021/10/29
  Time: 19:18
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<%
    request.setAttribute("key1", null);
%>

表达式脚本输出key1 = <%=request.getAttribute("key1") == null ? "" : request.getAttribute("key1")%><br/>
EL表达式输出key1 = ${key1}
</body>
</html>
